1. Field of the Invention
The present invention relates to a device for reading and writing on a magnetic support and to its production process. It is used in the production of rigid magnetic disk memories used in computers.
2. Discussion of Background
The reading and writing devices must be placed very close to the magnetic surface constituting the information support. In the case of a rigid support, such as e.g. a magnetic disk, the contact of the device with the disk may lead to surface defects and scratching. In order to reduce this risk, the magnetic reading and writing heads are fixed to a special support, whose surface e.g. is shaped like a catamaran. This shape enables the support to literally fly over the surface of the disk, the support being carried by the film of air which is entrained by the rotation of the disk. The flight height is generally less than 1 micron.
FIG. 1 shows in perspective view, a prior art device of this type. It comprises a support 12, whose flight or displacement surface 2 faces the disk. During operation, a pressure is exerted on the support, which can be compensated by a not shown load and localized in an upper slot 8. The leading face 6 of the catamaran has a chamfer-like configuration.
The device comprises two read and write heads 10 having an air gap 14. These heads are opposite to chamfer 6 and on a side face 16. This arrangement enables the air gaps 14 to be at the lowest point during the flight or displacement of the support, because the plane thereof is slightly inclined relative to that of the disk during its displacement.
The read and write heads 10 placed on the side face 16 of the support have a structure and a position which can be called vertical (or transverse or perpendicular) in the sense that they have two pole pieces substantially perpendicular to the recording support and separated by an air gap level with the surface of the flight or displacement plane. Each head also comprises an exciting and reading coil, whose plane is also perpendicular to the recording support. Thus, the assembly is oriented perpendicular to the displacement surface 2.
In order to produce catamaran profiles, like that of FIG. 1, use is made of the property of certain crystalline materials, such as silicon, according to which chemical etching of an orientation 100 crystal face leads to the appearance of chamfers oriented according to 111 crystal planes. This known procedure, called reticular etching, leads to the appearance of walls inclined by 55.degree. relative to the 100 plane.
Catamaran-like supports with vertical heads are described in the Japanese Patent Abstract published in Patents Abstracts of Japan, Vol 1, No. 103, p. 3310 E 77 of 13.9.1977 corresponding to Japanese Patent Application JP-A-52 36016 of 19.3.1977 entitled "Manufacturing Method for Floating Magnetic Head".
The reticular etching process for producing such a support is more particularly described in the Japanese Patent Abstract which appeared in Patents Abstracts of Japan, Vol. 1, No. 119, p. 4772 E 77 of 11.10.1977, corresponding to Japanese Patent Application JP-A-52 50711 of 23.4.1977 entitled "Process for the Production of Slider".
However, such devices with perpendicular heads suffer from a major disadvantage. In order to produce such a device, it is necessary to start from a thick silicon section, on one of whose faces is deposited the read and write heads (which corresponds to face 16). This is followed by the cutting of said section in a direction perpendicular to the face containing the heads. This leads to substrates which are subjected to reticular etching on a face perpendicular to the face containing the head (which corresponds to face 2).
Thus, such a process requires a thick silicon seciton (4 to 5 mm), which is expensive. Moreover, it is necessary to work along two perpendicular faces (faces 16 and 2), which requires complex equipment and technology. Finally, the electrical connections with the head coil must be established on the section of the support (face 16) and then brought onto the upper face, which is complicated.